Bipolar battery and bipolar battery stack

ABSTRACT

Disclosed is a bipolar battery with which thermal deterioration of the electrode body due to the generation of heat of tabs can be suppressed. The bipolar battery of the present disclosure includes a first member, a second member, and a laminate electrode body arranged therebetween, wherein the laminate electrode body includes a first current collector constituting a lamination direction end surface, a second current collector constituting the other lamination direction end surface, at least one bipolar current collector arranged between the first current collector and the second current collector, and a plurality of power generating elements which are electrically connected in series via the bipolar current collector between the first current collector and the second current collector, the first current collector is arranged between the first member and the bipolar current collector, the second current collector is arranged between the second member and the bipolar current collector, the first current collector has a first tab, the second current collector has a second tab, an amount of heat generated by the first tab during energization of the battery is greater than an amount of heat generated by the second tab, the first member is a cooling member for cooling the first current collector, and a cooling performance of the first member is greater than a cooling performance of the second member.

FIELD

The present application discloses a bipolar battery and a bipolarbattery stack.

BACKGROUND

Patent Literature 1 discloses a bipolar battery comprising a pluralityof bipolar electrodes laminated in series and electrolyte layersinterposed therebetween, wherein each bipolar electrode comprises apositive electrode formed on one surface of a current collector and anegative electrode formed on the other surface thereof. In PatentLiterature 1, outermost current collectors are provided on opposite endsof the plurality of bipolar electrodes in the lamination direction, andthe outermost current collectors are connected to the respective tabs(leads).

Patent Literature 2 discloses a battery pack in which cooling membersare provided between unit cells. Furthermore, Patent Literature 3discloses a battery cooling system, wherein an electrode block isarranged between battery electrode tabs, a cooling member is put incontact with the electrode block, and the electrode tabs are cooled viathe electrode block.

CITATION LIST Patent Literature

-   [PTL 1] WO 2006/062204-   [PTL 2] Japanese Unexamined Patent Publication No. 2019-036397-   [PTL 2] Japanese Unexamined Patent Publication No. 2012-248354

SUMMARY Technical Problem

In accordance with the new findings of the present inventors, in bipolarbatteries as disclosed in Patent Literature 1, during energization ofthe battery, the tabs connected to the outermost current collectorsgenerate heat, and the heat may diffuse from the tabs toward theinterior of the electrode body via the outermost current collectors. Inother words, there is a risk of thermal deterioration of part of theelectrode body due to the heat generated by the tabs. Furthermore, inaccordance with the new findings of the present inventors, the amount ofheat generated during energization of the battery differs between thepositive electrode side tab and the negative electrode side tab providedin the bipolar battery. Thus, it is considered that the above thermaldeterioration is likely to occur in the vicinity of the outermostcurrent collectors connected to the tabs, which generate significantquantities of heat.

Solution to Problem

As one means for solving the above problem, the present applicationdiscloses:

a bipolar battery, comprising a first member, a second member, and alaminate electrode body arranged between the first member and the secondmember, wherein

the laminate electrode body comprises a first current collectorconstituting a lamination direction end surface, a second currentcollector constituting the other lamination direction end surface, atleast one bipolar current collector arranged between the first currentcollector and the second current collector, and a plurality of powergenerating elements which are electrically connected in series via thebipolar current collector between the first current collector and thesecond current collector,

the first current collector is arranged between the first member and thebipolar current collector,

the second current collector is arranged between the second member andthe bipolar current collector,

the first current collector has a first tab,

the second current collector has a second tab,

an amount of heat generated by the first tab during energization of thebattery is greater than an amount of heat generated by the second tab,

the first member is a cooling member for cooling the first currentcollector, and

a cooling performance of the first member is greater than a coolingperformance of the second member.

In the bipolar battery of the present disclosure, the first tab may havea shutdown mechanism.

In the bipolar battery of the present disclosure, the second member maybe a heat insulating member.

As one means for solving the above problem, the present applicationdiscloses a bipolar battery stack comprising a plurality of the abovebipolar batteries of the present disclosure.

In the bipolar battery stack of the present disclosure, the secondmember of one of the bipolar batteries may be laminated on the firstmember of another bipolar battery.

In the bipolar battery stack of the present disclosure, the first memberof one of the bipolar batteries may be laminated on the first member ofanother bipolar battery.

In the bipolar battery stack of the present disclosure, the first memberis shared by one of the bipolar batteries and another of the bipolarbatteries.

Advantageous Effects of Invention

According to the technology of the present disclosure, the outermostcurrent collector (first current collector) which is connected to thefirst tab, which generates significant amounts of heat duringenergization, can be cooled by the first member. In other words, evenwhen heat is generated by the first tab, the heat is unlikely to spreadfrom the first tab toward the interior of the laminate electrode bodyvia the first current collector, whereby thermal deterioration of thelaminate electrode body due to the heat generated by the tab can besuppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing an example of the appearance of abipolar battery.

FIG. 2 is a schematic view showing the structure of a cross-sectiontaken along line II-II of FIG. 1 .

FIG. 3 is a schematic view showing an example of the appearance of abipolar battery stack.

FIG. 4A is a schematic view detailing the laminate structure of thebipolar battery stack shown in FIG. 3 . The exterior body has beenomitted.

FIG. 4B is a schematic view detailing another example of the laminatestructure of the bipolar battery stack. The exterior body has beenomitted.

FIG. 4C is a schematic view detailing another example of the laminatestructure of the bipolar battery stack. The exterior body has beenomitted.

FIG. 5 is a schematic view detailing an example of the structure of abipolar battery stack comprising a heat exchanger. The exterior body hasbeen omitted.

DESCRIPTION OF EMBODIMENTS

1. Bipolar Battery

The structure of a bipolar battery 100 is schematically illustrated inFIGS. 1 and 2 . The bipolar battery 100 comprises a first member 10, asecond member 20, and a laminate electrode body 30 arranged between thefirst member 10 and the second member 20. The laminate electrode body 30comprises a first current collector 31 constituting a laminationdirection end surface, a second current collector 32 constituting theother lamination direction end surface, at least one bipolar currentcollector 33 arranged between the first current collector 31 and thesecond current collector 32, and a plurality of power generatingelements 34 which are electrically connected in series via the bipolarcurrent collector 33 between the first current collector 31 and thesecond current collector 32. The first current collector 31 is arrangedbetween the first member 10 and the bipolar current collector 33. Thesecond current collector 32 is arranged between the second member 20 andthe bipolar current collector 33. The first current collector 31 has afirst tab 31 a. The second current collector 32 has a second tab 32 a.During energization of the battery 100, the amount of heat generated bythe first tab 31 a is greater than an amount of heat generated by thesecond tab 32 a. The first member 10 is a cooling member for cooling thefirst current collector 31. The cooling performance of the first member10 is greater than the cooling performance of the second member 20.

1.1 First Member

The first member 10 is a cooling member for cooling the first currentcollector 31. The shape, structure and material of the first member 10are not particularly limited as long as it is capable of cooling thefirst current collector 31. The first member 10 can be, for example, aplate-like member. Specifically, the first member 10 may be a coolingplate which removes heat from the first current collector 31.Alternatively, the first member 10 may be a cooling plate havingpassages of coolant. As will be described later, the first member 10 maybe connected to a heat exchanger 50 (refer to FIG. 5 ). For example,when the first member 10 has coolant passages, the coolant passages maybe connected to the heat exchanger 50.

As shown in FIG. 2 , an intermediate member such as an exterior body 40may be present between the first member 10 and the first currentcollector 31. Alternatively, the first member 10 may be in directcontact with the surface of the first current collector 31.

As shown in FIG. 2 , the first member 10 may be provided on only one endside (a position facing the surface of the first current collector 31)of the laminate electrode body 30 in the lamination direction.Alternatively, the first member 10 may have a portion which protrudesfrom the position facing the surface of the first current collector 31,and, for example, the first member 10 may be present on the side surfaceside of the laminate electrode body 30 by bending the protruding portion(refer to FIG. 5 ).

The cooling performance of the first member 10 is greater than thecooling performance of the second member 20. The phrase “coolingperformance of the first member 10” means the ability of the firstmember 10 to cool the first current collector 31. The phrase “coolingperformance of the second member 20” means the ability of the secondmember 20 to cool the second current collector 32. In other words, thephrase “the cooling performance of the first member 10 is greater thanthe cooling performance of the second member 20” means that when thethermal conductivity and heat generation amount of the first currentcollector 31 are the same as the thermal conductivity and heatgeneration amount of the second current collector 32, the amount of heatremoved from the first current collector 31 to the first member 10 perunit time is greater than the amount of heat removed from the secondcurrent collector 32 to the second member 20 per unit time. Note that aswill be described later, the second member 20 need not necessarily be acooling member, but rather may be, for example, an insulating member.When the second member 20 is an insulating member, the coolingperformance of the first member 10 will naturally be higher than thecooling performance of the second member 20.

1.2 Second Member

The second member 20 may be a cooling member which cools the secondcurrent collector 32, or may be a non-cooling member which is notintended to cool the second current collector 32. The shape, structure,and material of the second member 20 are not particularly limited aslong as the cooling performance thereof is less than that of the firstmember 10. The second member 20 may be a heat insulating member. Forexample, the second member 10 may be a plate-like insulating member forpreventing the spread of fire. Alternatively, the second member 20 maybe a resin frame for the retention of the laminate electrode body 30 orthe exterior body 40. Note that in the present application, such a resinframe is also regarded as a type of heat insulating member.

As shown in FIG. 2 , an intermediate member such as the exterior body 40may be present between the second member 20 and the second currentcollector 32. Alternatively, the second member 20 may be in directcontact with the surface of the second current collector 32.

Note that the bipolar battery of the present disclosure may include aform in which an intermediate member A is present between the firstmember 10 and the first current collector 31 and an intermediate memberB (A and B may be identical members or members of the same type or maybe different members) is present between the second member 20 and thesecond current collector 32. When an intermediate member(s) is presenton the first current collector 31 side and/or the second currentcollector 32 side in this manner, the cooling performance of the entirebody including the intermediate members is compared between the firstcurrent collector 31 side and the second current collector 32 side. Inother words, the cooling performance for the first current collector 31exhibited by the first member 10 and the intermediate member A is higherthan the cooling performance for the second current collector 32exhibited by the second member 20 and the intermediate member B.Intermediate members may be present between the first member 10 and thefirst current collector 31 and between the second member 20 and thesecond current collector 32 as long as the cooling performance is higheron the first current collector 31 side than on the second currentcollector 32 side.

As shown in FIG. 2 , the second member 20 may be provided only on theother end side (a position facing the surface of the second currentcollector 32) of the laminate electrode body 30 in the laminationdirection. Alternatively, the second member 20 may have a portion whichprotrudes from the position facing the surface of the second currentcollector 32, and, for example, the second member 20 may be present onthe side surface side of the laminate electrode body 30 by bending theprotruding portion.

1.3 Laminate Electrode Body

The laminate electrode body 30 is arranged between the first member 10and the second member 20. The bipolar battery 100 can be charged anddischarged by the battery reaction in the laminate electrode body 30. Asshown in FIG. 2 , the laminate electrode body 30 comprises the firstcurrent collector 31 constituting a lamination direction end surface,the second current collector 32 constituting the other laminationdirection end surface, the at least one bipolar current collector 33arranged between the first current collector 31 and the second currentcollector 32, and a plurality of power generating elements 34 which areelectrically connected in series via the bipolar current collector 33between the first current collector 31 and the second current collector32.

1.3.1 First Current Collector

The first current collector 31 constitutes a lamination direction endsurface of the laminate electrode body 30, and is arranged between thefirst member 10 and the bipolar current collector 33. In other words,the first current collector 31 is the outermost current collectorarranged more outwardly on the first member 10 side than the bipolarcurrent collector 33 of the laminate electrode body 30.

The first current collector 31 may be constructed from metal foil ormetal mesh. From the viewpoint of high handleability, the first currentcollector 31 may be metal foil. The first current collector 31 may becomposed of a plurality of layers of metal foil. Examples of the metalconstituting the first current collector 31 may include Cu, Ni, Cr, Au,Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. Some sort of coatinglayer may be included on the surface of the first current collector 31to adjust the resistance thereof. When the first current collector 31 iscomposed of a plurality of layers of metal foil, some sort of layer maybe included between the plurality of layers of metal foil. The thicknessof the first current collector 31 is not particularly limited. It maybe, for example, 0.1 μm or more or 1 μm or more, and may be 1 mm or lessor 100 μm or less.

The first current collector may be a positive electrode currentcollector or may be a negative electrode current collector. When thefirst current collector 31 is a positive electrode current collector,the second current collector 32, which will be described later, is anegative electrode current collector, and when the first currentcollector 31 is a negative electrode current collector, the secondcurrent collector 32, which will be described later, is a positiveelectrode current collector.

1.3.2 First Tab

The first current collector 31 comprises a first tab 31 a. Duringcharging of the bipolar battery 100, electrical power is supplied to thepower generating elements 34 via the first tab 31 a, and duringdischarging of the bipolar battery 100, electrical power is dischargedto the outside via the first tab 31 a. In other words, Joule heatgeneration due to energization can occur in the first tab 31 a duringboth charging and discharging of the bipolar battery 100.

The amount of heat generated by the first tab 31 a during energizationof the battery 100 varies in accordance with the material and shape ofthe first tab 31 a (cross-sectional area, length, etc.), energizationresistance with the members connected with the first tab 31 a fortransferring current (for example, increased electrical resistance dueto welding), and the Joule heat generation amount of the membersconnected to the first tab 31 a. The magnitude relationship between theamount of heat generated by the first tab 31 a and the amount of heatgenerated by the second tab 32 a can be confirmed by, for example,energizing the laminate electrode body 30.

The material of the first tab 31 a may be the same as the material ofthe first current collector 31 or may be different. The tab 31 a may becomposed of a material having a high volume resistivity (electricalresistivity) as compared with that of the second tab 32 a. The thicknessof the first tab 31 a may be the same as the thickness of the of thefirst current collector 31 or may be different. The cross-sectional areaof the first tab 30 may be smaller than the cross-sectional area of thesecond tab 32 a. It is sufficient that the first tab 31 a have a shapewhich protrudes from the first current collector 31. As the protrudingshape of the first tab 31 a, various shapes such as a polygonal shape, asemicircular shape, and a linear shape can be adopted. The method forproviding the first tab 31 a on the first current collector 31 is notparticularly limited. For example, the first tab 31 a may be formed bycutting out a part of the first current collector 31, or may be formedby connecting the first tab 31 a to the first current collector 31 bywelding or the like.

The first tab 31 a may have a shutdown mechanism. The phrase “shutdownmechanism” means a mechanism for cutting off the current or making itdifficult for current to flow when the first tab 31 a generatesexcessive heat, when excessive current flows through the first tab 31 a,or when the battery 100 is in an abnormal charging (overcharging) state.Specific examples of the shutdown mechanism include a heat-fusingmechanism, a mechanism using a PTC element, and a metal plate reversingmechanism by gas pressure. The phrase “heat-fusing mechanism” means thata notch (cut) is provided at the base of tab 31 a, and the notch (cut)is fused when the temperature rises or excessive current flows. Thephrase “a mechanism using a PTC element” means that a PTC material(mixture of a resin and a conductive material; barium titanate; etc.) isarranged in a part of the current path of tab 31 a, and when thetemperature rises, the resistance of the PTC material rises, making itdifficult for current to flow. The phrase “metal plate reversingmechanism by gas pressure” means that when the internal pressure of thebattery rises during overcharging and etc., the internal pressureinverts the metal plate, thereby cutting off the current (refer to, forexample, Japanese Unexamined Patent Publication No. 2018-77977). Whenthe first tab 31 a comprises a shutdown mechanism, the amount of heatgenerated during energization may be greater than when a shutdownmechanism is not provided.

1.3.2 Second Current Collector

The second current collector 32 constitutes the other laminationdirection end surface of the laminate electrode body 30, and is arrangedbetween the second member 20 and the bipolar current collector 33. Inother words, the second current collector 32 is the outermost currentcollector arranged more outwardly on the second member 20 side than thebipolar current collector 33 of the laminate electrode body 30.

The second current collector 32 may be constructed from metal foil ormetal mesh. From the viewpoint of high handleability, the second currentcollector 32 may be metal foil. The second current collector 32 may becomposed of a plurality of layers of metal foil. Examples of the metalconstituting the first current collector 31 may include Cu, Ni, Cr, Au,Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. Some sort of coatinglayer may be included on the surface of the second current collector 32to adjust the resistance thereof. When the second current collector 32is composed of a plurality of layers of metal foil, some sort of layermay be included between the plurality of layers of metal foil. Thethickness of the second current collector 32 is not particularlylimited. It may be, for example, 0.1 μm or more or 1 μm or more, and maybe 1 mm or less or 100 μm or less.

1.3.3 Second Tab

The second current collector 32 comprises a second tab 32 a. Duringcharging of the bipolar battery 100, electrical power is supplied to thepower generating elements 34 via the second tab 32, and duringdischarging of the bipolar battery 100, electrical power is dischargedto the outside via the second tab 32 a. In other words, Joule heatgeneration due to energization occurs in the second tab 32 a during bothcharging and discharging of the bipolar battery 100. However, the secondtab 32 a has a small amount of heat generated during energization thanthe first tab 31 a. Thus, even if the second tab 32 a generates heat, alittle or less heat diffuses into the second current collector 32.

The material of the second tab 32 a may be the same as the material ofthe second current collector 32 or may be different. The thickness ofthe second tab 32 a may be the same as the thickness of the secondcurrent collector 32 or may be different. It is sufficient that thesecond tab 32 a have a shape which protrudes from the second currentcollector 32. As the protruding shape of the second tab 32 a, variousshapes such as a polygonal shape, a semicircular shape, and a linearshape can be adopted. The method for providing the second tab 32 a onthe second current collector 32 is not particularly limited. Forexample, the second tab 32 a may be formed by cutting out a part of thesecond current collector 32, or may be formed by connecting the secondtab 32 a to the second current collector 32 by welding or the like.

The second tab 32 a may or may not comprise a shutdown mechanism. Whenthe first tab 31 a comprises a shutdown mechanism, the second tab 32 amay not comprise a shutdown mechanism.

1.3.4 Bipolar Current Collector

The bipolar current collector 33 is arranged between the first currentcollector 31 and the second current collector 32. In FIG. 2 , an aspectin which a plurality of bipolar current collectors 33 are provided inthe laminate electrode body 30 is shown, and the number of bipolarcurrent collectors 33 in the laminate electrode body 30 is notparticularly limited as long as it is at least one. However, the case inwhich a plurality of bipolar current collectors 33 are provided isconsidered to highly exhibit the effect of the technology of the presentdisclosure.

The bipolar current collector 33 may be constructed from metal foil ormetal mesh. From the viewpoint of handleability, the bipolar currentcollector 33 may be metal foil. The bipolar current collector 33 may becomposed of a plurality of layers of metal foil. Examples of the metalconstituting the bipolar current collector 33 may include Cu, Ni, Cr,Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. The metalsconstituting the first current collector 31, the second currentcollector 32, and the bipolar current collector 33 may be the same ormay be different. Some sort of coating layer may be included on thesurface of the bipolar current collector 33 to adjust the resistancethereof. Furthermore, when the bipolar current collector 33 is composedof a plurality of layers of metal foil, some sort of layer may beincluded between the plurality of layers of metal foil. The thickness ofthe bipolar current collector 33 is not particularly limited. Forexample, the thickness may be 0.1 μm or more and may be 1 μm or more,and may be 1 mm or less or 100 μm or less.

1.3.5 Power Generating Elements

It is sufficient that the power generating elements 34 be capable ofcausing a battery reaction to charge and discharge the bipolar battery100. For example, as shown in FIG. 2 , each power generating element 34may comprise a first active material layer 34 a, a second activematerial layer 34 b, and an electrolyte layer 34 c arranged between thefirst active material layer 34 a and the second active material layer 34b. The plurality of power generating elements 34 are electricallyconnected in series via the bipolar current collector 33.

Among the first active material layer 34 a and the second activematerial layer 34 b, one is a positive electrode active material layerand the other is a negative electrode active material layer. When thefirst active material layer 34 a is a positive electrode active materiallayer, the first current collector 31 described above can become apositive electrode current collector, and when the first active materiallayer 34 a is a negative electrode active material layer, the currentcollector 31 described above can become a negative electrode currentcollector. Furthermore, when the second active material layer 34 b is apositive electrode active material layer, the second current collector32 described above can become a positive electrode current collector,and when the second active material layer 34 b is a negative electrodeactive material layer, the second current collector 32 described abovecan become a negative electrode current collector.

The positive electrode active material layer comprises at least apositive electrode active material. When the bipolar battery 100 is asolid-state battery, in addition to a positive electrode activematerial, a solid electrolyte, a binder, and a conductive agent can beoptionally further included. Furthermore, when the bipolar battery 100is a liquid electrolyte-based battery, in addition to a positiveelectrode active material, a binder and conductive agent can beoptionally further included. A known active material may be used as thepositive electrode active material. Between two materials havingdifferent potentials for occlusion and release (charging and dischargingpotentials) of a predetermined type of ions, the material demonstratinga noble potential can be used as the positive electrode active materialand the material demonstrating a low potential can be used as a negativeelectrode active material, which is described later. For example, in thecase of constituting a lithium ion battery, various lithium-containingcomposite oxides such as lithium cobalt oxide, lithium nickel oxide,LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂, lithium manganate, and spinel-basedlithium compounds can be used as the positive electrode active material.When the bipolar battery 100 is a solid state battery, the surface ofthe positive electrode active material may be coated with an oxide layersuch as a lithium niobate layer, a lithium titanate layer, or a lithiumphosphate layer. When the bipolar battery 100 is a solid state battery,the solid electrolyte is preferably an inorganic solid electrolyte. Thisis because the ionic conductivity thereof is higher than that of organicpolymer electrolytes. This is also because it has excellent heatresistance as compared with organic polymer electrolytes. Further, thisis because it has excellent rigidity as compared with organic polymerelectrolytes, whereby the bipolar battery 100 can be more easilyconstructed. Examples of preferred inorganic solid electrolytes mayinclude oxide solid electrolytes such as lithium lanthanum zirconate,LiPON, Li_(1+X)Al_(X)Ge_(2−X)(PO₄)₃, Li—SiO-based glasses, andLi—Al—S—O-based glasses; and sulfide solid electrolytes such asLi₂S—P₂S₅, Li₂S—SiS₂, LiI—Li₂S—SiS₂, LiI—Si₂S—P₂S₅, Li₂S—P₂S₅—LiI—LiBr,LiI—Li₂S—P₂S₅, LiI—Li₂S—P₂O₅, LiI—Li₃PO₄—P₂S₅, and Li₂S—P₂S₅—GeS₂. Inparticular, sulfide solid electrolytes are preferred, and sulfide solidelectrolytes comprising Li₂S—P₂S₅ are more preferable. Examples of thebinder included in the positive electrode active material layer mayinclude butadiene rubber (BR) based binders, butylene rubber (IIR) basedbinders, acrylate butadiene rubber (ABR) based binders, polyvinylidenefluoride (PVdF) based binders, and polytetrafluoroethylene (PTFE) basedbinders. Examples of the conductive agent included in the positiveelectrode active material layer may include carbon materials such asacetylene black and Ketchen Black or metal materials such as nickel,aluminum, and stainless steel. The content of each component in thepositive electrode active material layer may be the same as in the priorart. The shape of the positive electrode active material layer may alsobe the same as in the prior art. In particular, from the viewpoint offacilitating construction of the bipolar battery 100, a sheet-likepositive electrode active material layer is preferred. The thickness ofthe positive electrode active material layer is not particularlylimited. For example, the thickness may be 0.1 μm to 2 mm. The lowerlimit thereof may be 1 μm or more and the upper limit thereof may be 1mm or less.

The negative electrode active material layer comprises at least anegative electrode active material. When the bipolar battery 100 is asolid state battery, in addition to the negative electrode activematerial layer, a solid electrolyte, binder, and conductive agent canfurther be optionally included. Furthermore, when the bipolar battery100 is a liquid electrolyte-based battery, in addition to the negativeelectrode active material, a binder and a conductive agent can beoptionally further included. A known active material may be used as thenegative electrode active material. For example, when the battery isconstituted as a lithium ion battery, a silicon-based active materialsuch as Si, Si alloys, and silicon oxide; a carbon-based active materialsuch as graphite or hard carbon; various oxide-based active materialssuch as lithium titanate; metallic lithium and lithium alloys can beused as the negative electrode active material. The solid electrolyte,the binder and the conductive agent can be appropriately selected andused from those exemplified for the positive electrode active materiallayer. The content of each component in the negative electrode activematerial layer may be the same as in the prior art. The shape of thenegative electrode active material layer may also be the same as in theprior art. In particular, from the viewpoint of facilitatingconstruction of the bipolar battery 100, a sheet-like negative electrodeactive material layer is preferred. The thickness of the negativeelectrode active material layer is not particularly limited. Forexample, the thickness may be 0.1 μm to 2 mm. The lower limit thereofmay be 1 μm or more and the upper limit thereof may be 1 mm or less.

The electrolyte layer 34 c comprises at least an electrolyte. When thebipolar battery 100 is a solid state battery, the electrolyte layer 34 ccan be a solid electrolyte layer comprising a solid electrolyte andoptionally a binder. The solid electrolyte is preferably an inorganicsolid electrolyte, as described above, and is particularly preferably asulfide solid electrolyte. The binder can be appropriately selected andused from among those used for the positive electrode active materiallayer. The content of each component in the solid electrolyte layer maybe the same as in the prior art. The shape of the solid electrolytelayer may also be the same as in the prior art. In particular, from theviewpoint of facilitating construction of the bipolar battery 100, asheet-like solid electrode layer is preferred. In this case, thethickness of the solid electrolyte layer may be, for example, 0.1 μm to2 mm. The lower limit thereof may be 1 μm and the upper limit thereofmay be 1 mm. Conversely, when the bipolar battery 100 is a liquidelectrolyte-based battery, the electrolyte layer 34 c can comprise aliquid electrolyte and a separator. Known liquid electrolytes andseparators may be used. Note that when comparing the case in which theelectrolyte layer 34 c is a liquid electrolyte layer and the case inwhich it is a solid electrolyte layer, in the case in which theelectrolyte layer 34 c is a solid electrolyte layer, construction of thebipolar battery 100 is considered to be easier.

The power generating elements 34 and laminate electrode body 30 can beproduced by known methods. The number of the plurality of powergenerating elements 34 included in the laminate electrode body is notparticularly limited. For example, the number of power generatingelements 34 may be 2 to 1000. The lower limit thereof may be 10 or more,and the upper limit may be 300 or less.

Note that though the shape of the laminate surface (the surface shape ofthe first current collector 31) of the laminate electrode body 30 isillustrated as rectangular in FIGS. 1 and 2 , the shape of the laminatesurface of the laminate electrode body 30 is not limited thereto.

1.3.6 Other Members

In addition to the first member 10, the second member 20, and thelaminate electrode body 30 described above, the bipolar battery 100 maycomprise other members. For example, terminals connected to the tabs 31a, 32 a may be provided. The terminals may be mechanically connected totabs 31 a and 32 a so as to be detachable, or may be joined by welding.

As described above, the bipolar battery 100 may comprise an exteriorbody 40 for accommodating the laminate electrode body 30. In this case,the first member 10 may cool the first current collector 31 via theexterior body 40. The exterior body 40 may be a laminate film or may bea metal case. However, even if an exterior body 40 is not provided, thebipolar battery can be constructed. For example, the side surfaces ofthe laminate electrode body 30 in the lamination direction may be sealedwith a resin, and the sealing resin, the first current collector 31, andthe second current collector 32 may serve the same function as theextender body. In this case, the first member 10 may be in directcontact with the first current collector 31, whereby the first currentcollector 31 can be directly cooled.

As will be described later, the bipolar battery 100 may be connected toa heat exchanger 50. As a result, the cooling efficiency of the firstcurrent collector 31 by the first member 10 is further improved.

2. Bipolar Battery Stack

The technology of the present disclosure also includes an aspect as abipolar battery stack. In other words, the bipolar battery stack of thepresent disclosure comprises a plurality of the bipolar batteries of thepresent disclosure described above. For example, the bipolar batterystack may be constructed by laminating a plurality of the bipolarbatteries. The method for laminating the bipolar batteries is notparticularly limited.

2.1 First Aspect

FIGS. 3 and 4A show a bipolar battery stack 1000 according to a firstaspect. As shown in FIGS. 3 and 4A, in the bipolar battery stack 1000,the second member 20 of one bipolar battery 100 may be laminated on thefirst member 10 of another bipolar battery 100. In other words, in thebipolar battery stack 1000, one bipolar battery 100 and another bipolarbattery 100, which are adjacent, may be laminated in the same direction.

2.2 Second Aspect

FIG. 4B shows a bipolar battery stack 2000 according to a second aspect.As shown in FIG. 4B, in the bipolar battery stack 2000, the first member10 of one bipolar battery 100 may be laminated on the first member 10 ofanother bipolar battery 100. Furthermore, as shown in FIG. 4B, in thebipolar battery stack 2000, the second member 20 of one bipolar battery100 may be laminated on the second member 20 of another bipolar battery100. In other words, in the bipolar battery stack 2000, one bipolarbattery 100 and another bipolar battery 100, which are adjacent, may belaminated in mutually opposite directions.

2.3 Third Aspect

FIG. 4C shows a bipolar battery stack 3000 according to a third aspect.As shown in FIG. 4C, in the bipolar battery stack 3000, a first member10 may be shared by one bipolar battery 100 and another bipolar battery100. Furthermore, as shown in FIG. 4C, in the bipolar battery stack 300,a second member 20 may be shared by one bipolar battery 100 and anotherbipolar battery 100. In other words, in the bipolar battery stack 3000,first members 10 and second members 20 may be shared between adjacentbipolar batteries 100 while omitting some first members 10 and somesecond members 20.

2.4 Other Aspects

As in the bipolar battery stack 4000 shown in FIG. 5 , the first member10 may be connected to a heat exchanger 50. For example, when the firstmember 10 has coolant passages, the coolant passages may be connected tothe heat exchanger 50, whereby coolant may be circulated between theheat exchanger 50 and the first member 10. The location where the heatexchanger is connected in the bipolar battery stack is not particularlylimited. Among the side surfaces (the surfaces other than the laminatedsurfaces) of the bipolar battery 100, when the surface on which tabs 31a, 32 a protrude is the first side surface, the surface opposite to thefirst side surface is the second side surface, and the two side surfacesbetween the first side surface and the second side surface are the thirdside surface and the fourth side surface, the heat exchanger 50 may beconnected to the second side surface of the bipolar battery 100, or theheat exchanger 50 may be connected to the third side surface or fourthside surface.

The bipolar battery stack may comprise arbitrary members other thanthose described above. For example, wiring or a stack case may beprovided.

3. Effects

In conventional bipolar batteries, during energization of the battery,the tabs connected to the outermost current collectors generate heat,and this heat may diffuse from the tabs toward the interior of theelectrode body via the outermost current collectors. The amount of heatgenerated during energization of the battery differs between thepositive electrode side tab and the negative electrode side tab providedin the bipolar battery. For example, when one tab is composed of Al andthe other tab is composed of Cu, and the shapes of both tabs are thesame, since the electrical resistivity of Al is greater than that of Cuand the thermal conductivity of Al is less than that of Cu, the tabcomposed of Al has a greater amount of heat generated duringenergization and has a lower heat dissipation capacity than the tab madeof Cu. Thus, when comparing the current collector connected to Al taband the current collector connected to Cu tab, a significant amount ofheat is conducted and diffused to the former current collector, andthermal deterioration of the electrode body is likely to occur in thevicinity of the former current collector. In connection thereto,according to the bipolar battery of the present disclosure, theoutermost current collector (first current collector) connected to thetab (first tab) having a significant amount of amount of heat generatedduring energization can be appropriately cooled by the first member,which has high cooling performance. As a result, thermal deteriorationof the laminate electrode body in the vicinity of the first currentcollector connected to the first tab, which generates significantamounts of heat, can be suppressed.

INDUSTRIAL APPLICABILITY

The bipolar battery and bipolar battery stack of the present disclosureis widely applicable, from small power sources such as those for mobiledevices to large power sources, such as those for electric vehicles.

REFERENCE SIGNS LIST

-   10 first member-   20 second member-   30 laminate electrode body-   31 first current collector-   31 a first tab-   32 second current collector-   32 a second tab-   33 bipolar current collector-   34 power generating element-   34 a first active material layer-   34 b second active material layer-   34 c electrolyte layer-   40 exterior body-   50 heat exchanger-   100 bipolar battery-   1000, 2000, 3000, 4000 bipolar battery stack

The invention claimed is:
 1. A bipolar battery comprising a firstmember, a second member, and a laminate electrode body arranged betweenthe first member and the second member, wherein the laminate electrodebody comprises a first current collector constituting a laminationdirection end surface, a second current collector constituting the otherlamination direction end surface, at least one bipolar current collectorarranged between the first current collector and the second currentcollector, and a plurality of power generating elements which areelectrically connected in series via the at least one bipolar currentcollector between the first current collector and the second currentcollector, the first current collector is arranged between the firstmember and the at least one bipolar current collector, the secondcurrent collector is arranged between the second member and the at leastone bipolar current collector, the first current collector has a firsttab, the second current collector has a second tab, an amount of heatgenerated by the first tab during energization of the battery is greaterthan an amount of heat generated by the second tab, the first member isa cooling member for cooling the first current collector, and a coolingperformance of the first member is greater than a cooling performance ofthe second member.
 2. The bipolar battery according to claim 1, whereinthe first tab has a shutdown mechanism.
 3. The bipolar battery accordingto claim 1, wherein the second member is a heat insulating member.
 4. Abipolar battery stack, comprising: a plurality of the bipolar batteriesaccording to claim
 1. 5. The bipolar battery stack according to claim 4,wherein the second member of one of the bipolar batteries is laminatedon the first member of another bipolar battery.
 6. The bipolar batterystack according to claim 4, wherein the first member of one of thebipolar batteries is laminated on the first member of another bipolarbattery.
 7. The bipolar battery stack according to claim 4, wherein thefirst member is shared by one of the bipolar batteries and another ofthe bipolar batteries.